Apparatus for automatically measuring the light transmission factor or liquid test samples

ABSTRACT

An apparatus for automatically measuring the light transmission factor of liquid test samples in which a number of transparent vats is arranged around the circumference of a stationary table over which rotates a photoelectric measuring device which successively scans each vat to determine the light transmission factor of the samples. The various samples are automatically transferred by sucking them into the measuring vats from a bank of test tubes via a bank of probes with flexible hose connections to each vat; a central control valve drains the vats after testing. Electronic timing circuits provide the control commands for the operative sequences of the device, and logic circuitry, in combination with a data storage and retrieval system, provides comparative data between reference measurements and sample measurements for each vat.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to light transmission measuring devices,and in particular to devices which are capable of automaticallymeasuring the light transmission factor of succession of liquid testsamples, such as cultures of micro-organisms, for example cultures andthe like, and of interpreting and storing the test results.

2. Description of the Prior Art

The measurement of the light transmission factor of certain test samplesis an important parameter in the comparison of liquid microorganiccultures. In the past, such measurements were obtained by means ofdevices which included a sampling vat, or measuring vat, into which thevarious liquid test samples were introduced successively formeasurement. In some instances, a limited number of separate measuringvats was used.

For large laboratories, which had to examine a large number of liquidtest samples, it was therefore necessary to have several of thesedevices which had to be operated by a corresponding number of personnel.Such a situation can result in a very costly testing operation, and italso increases the risk of errors which have potentially graveconsequences, especially in the pharmaceutic industry.

SUMMARY OF THE INVENTION

It is a primary objective of the present invention to overcome theaforementioned shortcominings, by suggesting an apparatus for theautomatic measurement of the light transmission factor of a large numberof liquid test samples in a reliable, high-speed procedure which alsopermits the convenient interpretation and storage of the test resultsobtained.

The invention proposes to attain the above objective by suggesting anapparatus for automatically measuring the light transmission factor ofliquid test samples which is characterized in that it includes a seriesof transparent measuring vats which are arranged at regular intervalsalong a circumference, each vat being designed to receive a liquid testsample, the apparatus further including a means for simultaneouslyintroducing a separate sample into each measuring vat and forsimultaneously draining these samples from all measuring vats, a meansfor successively measuring the light transmission factor of each samplein its measuring vat and for furnishing an electronic signal indicativeof the coefficient of light transmission of each liquid sample, a meansfor processing and recording these signals, and a means for controllingthe timing sequence of the sample transfer operation, of the sampledraining operation, and of the measuring operation.

In a preferred embodiment of the invention, the sample transfer meansand sample draining means include a separate suction probe for eachmesuring vat, connected thereto by a flexible hose, and a verticallymovable platform under the bank of probes, the platform being arrangedto receive a matching bank of test tubes which contain the varioussamples of culture liquid to be tested. The suction probes thus have thesame spacing as the test tubes on the platform, so that when the latteris raised against the suction probes, and a negative pressure is appliedto the measuring vats via a central control valve, each separate liquidsample is drawn into its corresponding measuring vat. During thistransfer procedure and during the subsequent sequential measurement ofeach vat contents, the various liquid test samples remain isolated fromeach other. Following termination of the measurements, the test samplesare simultaneously drained from the measuring vats through anotheroperation of the central control valve, whereby all test liquid samplesare collected inside a tank prior to final disposal.

A preferred embodiment of the invention further suggests an apparatuswhich includes a rotating platform whose rotary axis is the center ofthe circumference on which the measuring vats are charged. The rotatingplatform of the apparatus includes a bridge which straddles themeasuring vats on the circumference of the stationary table, the bridgecarrying a light source and an optical measuring system facing the lightsource on the other side of the measuring vats. The light which travelsfrom the light source through the transparent walls of the measuring vatis transmitted to a photosensitive device and interperted in the form ofan electronic signal, the signal being transmitted to a stationaryelectronic signal treatment and interpretation unit over rotary contactson the indexing table.

BRIEF DESCRIPTION OF THE DRAWINGS

Further special features and advantages of the invention will becomeapparent from the description following below, when taken together withthe accompanying drawings which illustrate, by way of example, anembodiment of the invention, represented in the various figures asfollows:

FIG. 1 is a schematic elevational representation of an apparatus forautomatically measuring the light transmission factor of liquid testsamples, embodying the invention;

FIG. 2 shows in an elevational cross section the major mechanicalcomponents of the embodiment of FIG. 1;

FIG. 3 shows the lower portion of the machine of FIG. 2 in a differentoperating position;

FIG. 4 shows the machine of FIG. 2 in a plan view;

FIG. 5 shows an enlarged cross sectional detail representing themeasuring bridge of the embodiment of FIG. 2; and

FIG. 6 is a logic diagram of the controls of the machine of theinvention, as represented by the embodiment of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the apparatus of the invention includes a circularstationary table 1, and mounted on the periphery of this table aplurality of regularly spaced measuring vats 2 with transparent sidewalls. These measuring vats may be of the kind described in French Pat.No. 1,538,351, which discloses a sampling vat designed for automatictransfer and removal of the contents.

Each vat 2 is connected by a flexible transfer hose 3 to a transferprobe 4 in the form of a small, pipette-like tube. The probe 4 operatesin the manner of a hypordermic needle, after introducton into a testtube 5 containing the liquid sample to be studied.

The probes 4 are arranged in a regularly patterned bank on a rectangularsupport plate 6 (FIG. 4), the latter carrying parallel rows of regularlyspaced probes 4 in vertical alignment with a similar bank of test tubes5 arranged on a platform 7 which is part of a support bracket 8. Thelatter is arranged for vertical motion along vertical guides 10, beingdriven by an electric motor 9 and a crank drive 64.

The bracket 8 thus moves between a lower position, in which the probes 4are above and outside the test tubes 5, and a upper position in whichthe test tubes 5 are penetrated by the transfer probes 4.

The apparatus of the invention contains an equal number of measuringvats 2 and transfer probes 4. Each vat 2 is also individually linked toa flexible suction hose 11 which can be connected to a common source ofnegative pressure (not shown in the drawing) and which, when connectedthereto, creates a suction effect in the vat, thereby drawing the testsample from their test tubes 5, via the probes 4 and transfer hoses 3,into the respective measuring vats 2. A flexible drain hose 13 linkseach measuring vat 2 to a common control valve 12, through which theliquid samples can be emptied simultaneously via two lines 14 into adrain tank 15. The contents of tank 15 can be drained through a pipe 16and a drain valve 30 into a drain (not shown). The central control valve12 may be either a rotary valve with several control positions, or asolenoid-operated valve which is arranged to perform the followingoperations:

a. The simultaneous connection of all measuring vats 2 to a commonsource of negative pressure which causes the various test samples to bedrawn into their respective vats 2;

b. The separation of the measuring vats 2 from the drain tank 15 andfrom each other so as to retain the liquid samples in their vats duringthe entire measuring operation; and

c. The simultaneous connection of all the vats 2 with drain tank 15 forthe draining of their contents into the tank 15.

The function of the drain valve of waste tank 15 may also beincorporated in the function of the central control valve 12.

Above table 1 is arranged a rotary platform 17 which is driven by anelectric motor 18 via a reduction gear 19. The rotary platform 17carries on its periphery a bridge 20 in the form of an inverted "U"which is so arranged that it passes over the successively positionedmeasuring vats 2, the vertical legs 21 and 24 of bridge 20 beingpositioned on opposite sides of the vat profile.

The outer vertical leg 21 of bridge 20 further includes a horizontalextension 22 on which is mounted a light source 23. On the inner leg 24of bridge 20 is mounted a photosensitive device 25 which is arranged toreceive the light bundle which is emitted by light source 23 and whichhas traversed the vat 2 and its contents. The photosensitive device 25is connected to an electronic device 26 which transforms the signalsfrom the photosensitive device 25 into easily processable electronicinformation data.

The electronic device 26 is further connected to an electronic controlunit 28 which operates as a timing device and as an information storagedevice, the connecting lines including rotary contacts 27 arranged onthe rotating platform 17.

The major portions of this apparatus are illustrated in more detail inFIG. 2. It shows the stationary support table 1 on which are mounted themeasuring vats 2 and the rotary platform 17, as well as the bank oftransfer probes 4. The measuring vats 2 are mounted at regular intervalson a ring profile 32 which in turn is supported on the stationary table30 by means of spacers 31. Near the periphery of table 30 is furtherarranged an opening 33 in alignment with the vertically movable bracket8, the opening 33 being of rectangular outline and carrying a matchingsupport plate 6 for the withdrawal probes 4 of the apparatus. Thevat-side ends of the flexible transfer hoses 3 linking each probe 4 toone of the measuring vats 2 and the flexible suction hoses 11 linkingthe measuring vats 2 to the common control valve 12, as shown in FIG. 1,are preferably embedded inside suitable lateral vertical grooves in theend walls of the vats 2 which are oriented perpendicularly to theirtransparent walls.

In the middle of support table 1 is further arranged a circular opening34 through which extends a column assembly 35 which forms a verticalbearing support for the rotary platform 17. The column 35 is attached toa horizontal flange 36 which is supported by several studs 37 mounted ina second flange 38, which in turn is connected to the stationary supporttable 1 by means of studs 39. The flange 36 is traversed vertically by ahollow arbor 40 which is rigidly connected to the flange and on whoselower extremity is arranged an electrical connector plug 41. Aconducting rod 42 extends through the bore of arbor 40 so as to link theplug 41 with a contact blade 43 arranged above the rotary table 17. Tothe blade 43 is connected a lead which supplies electric power to thedevices mounted on the rotating platform 17.

The stationary arbor 40 is surrounded by a bearing sleeve 44 which isattached to the lower side of platform 17. Insulating sleeves betweenthe arbor 40 and the bearing sleeve 44 serve as radial bearing guides.The bearing sleeve 44 is further provided with a flange portion 36 whichcarries a spur gear ring 47 whose teeth are engaged by a pinion mountedon the drive shaft of an electric motor 18 (FIG. 1) which serves todrive the rotary platform 17. Underneath the flange portion 46 isattached a printed circuit panel 48. The bearing sleeve 44, and theplatform 17 supported by it, are in turn supported vertically on theflange 36 by means of a ball thrust bearing 49.

The bridge 20, which is mounted on the rotating platform 17 andindicated schematically in FIG. 1 as an extension thereof, includes anoffset support arm 50 which is attached to the platform by means of anintermediate base block 51 and a vertical support block 52. The supportarm 50 further includes a horizontal extension 53 on which is mounted alight source 23. The latter is preferably a quartz-iodine lamp.

In the vertical portion 54 of support arm 50 is mounted an opticalsystem 55 whose purpose is to align the light bundle emitted by lightsource 23 in the direction of the measuring vats 2. In the supportingblock 52 is similarly mounted another optical system 56 which isarranged to condense the light bundle passing through the measuring vat2 into a suitable beam which can be measured by a photoelectric cell.The support block 52 further carries on its side facing away from themeasuring vats 2 a photoelectric cell 58 which is supported by amounting sleeve 57. This photoelectric cell may be a vacuum cell of the"Boutry"-type which converts the light beam received through themeasuring vats 2 into an electrical signal. To the output side of thephotoelectric cell 58 is connected an amplifier-discriminator device 59which transforms the signals received from the cell 58 into easilytransmissible electrical signals.

The devices mounted on the rotating platform 17 are protected by a cover60, while a second protective cover 16 is fixedly mounted on verticalsupports such as the support profile 61 which is attached to thestationary table 1.

The vertically movable bracket 8 which carries the bank of test tubes 5containing the samples to be measured is mounted on one side of agliding hub 63 which is vertically movable along parallel vertical guideblocks 63a. It receives its vertical movement through a crank 64 whichis mounted on the drive shaft of an electric motor 9.

FIG. 3 shows a detail cross section of the arrangement of bracket 8 andits reciprocating drive, the guide rod 63a for the gliding hub 63 beingshown between two support columns 67 which carry an upper end plate 66.The gliding hub 63 is supported on the vertical guide rod 63a by meansof two bushings 68 which may be in the form of ball bushings. To the endof crank 64 is attached a follower 70 supported by a short arbor 71, thefollower 70 engaging a horizontal guide 69 on the gliding hub 63. Theelectric motor 95, as well as th columns 67 and 63a which support andguide the movable bracket 8, are mounted on a base plate 72.

The bridge, which is constituted by the vertical support 52 and theoffset support arm 50, is shown in more detail in FIG. 5. It shows howthe light source 23 is mounted on the horizontal extension 53 of supportarm 50 in connection with an adjustment means which includes ahorizontal plate 73 on which rests the light source 23 itself, and intowhich is screwed a threaded rod 74 which passes through the counterplate 75 on the upper side of the horizontal extension 53 of support arm50. On the rod 72 is arranged a compression spring 76 which is receivedinside an opening 77 in the horizontal extension 53 and which bearsagainst the counter plate 75 and against a washer 78 which is retainedon rod 74 by means of a nut 79.

The optical system 55 which is mounted in the vertical portion ofsupport arm 50 includes a housing 80 which holdes a heat-restrainingglass 81 facing the light source 23 and two plano-convex lenses 82 whichare mounted inside a mounting sleeve 83, the latter being retained inthe center bore of housing 80 by means of a threaded ring 84. Alsoarranged inside housing 80, on the side facing toward the measuring vats2, is an adjustable head 85 which carries an optical filter 86, adiaphragm 87, and a plano-convex lense 88 which is held by a threadedend ring 89.

The second optical system 56 which is supported by the vertical support52 is aligned with the first optical system 55 at the opposite of thevat profile. It includes a housing 90 inside which is movably arrangedan optical support 91. The optical support 91 holds a fiber opticalassembly 92 which condenses the light bundle received from the measuringvat into a narrower light beam. Opposite the smaller outlet end of thefiber optical assembly 92 is positioned an optical filter 93.

The photosensitive cell 58 which is placed at the exit side of theoptical system 56 may for example be a vacuum cell of the "Boutry"-type.This device is known and therefore not further described here. The sameapplies to the amplifier-discriminator device 59 which is likewise of aknown, conventional design.

According to a preferred embodiment of the invention, the operativecontrol of the apparatus shown in FIGS. 1-5 is provided by means of acontrol unit 28, which is shown in FIG. 1 and whose function isexplained in more detailed by the operation diagram of FIG. 6. In thatfigure, the scanning apparatus, which includes the measuring vats 2 ofthe rotating platform 17, is indicated at reference numeral 100.

The rotary contact 101 of the scanning device is connected to thecontact blade 102a of a two-way switch 102 which has two coupled contactblades 102a and 102b, the contact blade 102b being connected to the exitside of a reference value reader 103, via an intermediate converter 104.The device 103 may be a punched tape reader.

The movable contact 102a cooperates with two fixed contacts 105a and105b. Contact 105a is connected directly to the entrance of asignal-to-time converter 106, while contact 105b is connected toconverter 106 via an intermediate circuit 107 which compares a referenceor calibration value with the value actually measured on a sample byscanning device 100 to produce a quotient or difference signal. Themovable contact 102b cooperates with two fixed contacts 108a and 108b,but only contact 108b connecting the converter 104 to circuit 107 isused. The converter 106 includes an entry 111 to which is connected acircuit 112 from which it receives a control signal for the measurementof each vat.

The circuit 112 is also connected to a circuit 113 which controls theadvance of the punched tape in the reference value reader 103, and toauthorization circuit 114 which controls the registration of themeasurement data. The exit of converter 106 is connected to the entranceof a pulse counter 115 over an intermediate AND-gate 109 whose secondentrance is connected to a pulse generator 110. A second entrance ofcounter 115 is connected to a count authorization circuit 116. Thecontrol circuit 113, the authorization circuit 114, the counter 115, andthe authorization circuit 116 constitute the logic counting unit 117 ofthe apparatus.

The authorization circuit 116 is connected to another logic unit 118which controls the mechanical operations of the apparatus. It includes aposition verifying device 119 responding to the positions of the centralvalve 12 (FIG. 1) and of the vertically moving bracket 8, the positionverifying device 119 being controlled by a pulse generator 120 whichproduces a control signal during each revolution of the rotatingplatform 17. The position verifying device 119 is connected to anauthorization circuit 121 which serves to initiate the functions oftransferring the liquid samples into the measuring vats 2, oftranquilizing the samples inside those vats, of measuring each vat, andlastly, of draining the samples from the vats.

The authorization circuit 121 is connected to a motion control device122 which initiates the various movements of the apparatus and which islinked to the drive motors 9 and 18 for the rotating platform 17 and forthe reciprocating bracket 8 (FIG. 1). Circuit 121 is further connectedto a second control circuit 123 which controls the advance of thepunched tape through the reference value reader 103. The logic units 117and 118 are synchronized in their operation by means of a time piece124.

The exit of pulse counter 115 is connected to a three-stage countingassembly 125, 126, 127 which counts, respectively, the units, tens, andhundreds and which is controlled by authorization circuit 114 for thedata registration. The three counting stages 125, 126 and 127 areconnected to a data storage control device 128 which in turn isconnected to a data storage device which records the data received fromthe counters. The latter is preferably a tape punch.

The apparatus of the invention thus performs the following functionsduring the course of a measurement cycle:

1. Upward motion of the bracket 8 which carries the platform with thetest tubes 5 containing each a liquid sample to be measured.

2. Transfer of each liquid sample from one of the test tubes 5 into acorresponding measuring vat 2.

3. Separation of the measuring vats 2 from one another and from thedrain tank 15 (FIG. 1).

4. Measurement of the light transmission factor of each test sample.

5. Draining of the measuring vats 2.

6. Lowering of the bracket 8.

7. At the end of the cycle, preparation of the apparatus for a newcycle.

8. Draining of the drain tank 15, subject to the quantity of liquidcontained in each set of test tubes 5 and to the capacity of the tank.

The rotating platform of the apparatus which has just been described ispreferably advanced in a continuous rotary motion. Thus, themeasurements are made "on the fly," at the moment the light source 23and the associated optical systems 55 and 56 (FIG. 2) move past themeasuring vat 2.

The various operations of a complete measurement cycle are controlled bythe control logic of FIG. 6, and they are as follows:

Initially, the measuring vats 2 are filled with a control liquid and aseries of reference measurements is performed during which the switch102 of the logic of FIG. 6 has been placed so that the movable contactblades 102a and 102b are aligned with the fixed contacts 105a and 108a,respectively. Following conversion of the values obtained from themeasurement of the reference liquid into numerical values by means ofcircuits 106, 115 and 125, 126, 127, these numerical signals, whichrepresent reference or calibration values, are recorded by the tapepunch 129, each value of each measurement being associated with theidentification number of a vat 2. This punched tape is now placed intohe reference value reader 103. The reference values thus obtained may beused as long as their validity is not subject to question.

Once the reference values have been obtained and recorded, one canproceed with the measurement of a series of specific samples, which isas follows:

Following transfer of the liquid samples into the measuring vats 2 andisolation of the individual measuring vats, the measurement cycle isinitiated, while the switch 102 is in the position in which the fixedcontacts 105b and 108b are connected. The circuit 107 now receivessimultaneously the signal which is generated by a measurement operationon a vat containing a specific liquid sample and the reference signalfor this same vat containing the reference liquid, the reference signalbeing received from the reference value reader 103 in synchronism withthe rotation of the rotating platform 17. The reference signal istransmitted to circuit 107 through the intermediary of converter 104. Atthe exit of circuit 107 are obtained signals which correspond in eachcase to the ratio between the light transmission factor measured on aspecific liquid sample contained in a vat 2 and the light transmissionfactor measured on the reference liquid which had been measured in thissame vat.

The output signals of circuit 107 are then transformed by theamplitude-to-time converter 106 into time-referenced signals andtransformed into pulse trains by means of the circuits 110 and 109,these pulse trains being then counted and recorded on a punched tape bymeans of tape punch 129. The punched tape thus obtained provides aconvenient record of the relative light transmission coefficients of agreat number of liquid culture samples.

Knowing the relationship between the light transmission coefficient andthe evolutionary state of a sample, it is thus possible to quickly andconveniently study the results which are recorded on the punched tape,in order to obtain the necessary information. For the latter purpose,the punched tapes may be processed by a computer.

The logic device of FIG. 6 controls the various operations of theapparatus of the invention in the following manner:

The platform 17 is rotated by means of motor 18, a tray filled with testtubes 5, each containing a reference liquid, is placed on top of bracket8 in its lower position, and the switch 102 is placed so as to connectthe fixed contacts 105a and 108a.

The logic circuit 118, which now receives a start signal from anattendant-actuated signal source (not shown), initiates the operation ofmotor 65 (FIG. 2) through the action of control circuit 122. As a resultof the rotation of motor 9, the reciprocating bracket 8 is raised bymeans of the crank 64 and the gliding hub 62 to which it is attached,into the upper position (FIG. 2) in which the withdrawal probes 4 aredipped into their respective test tubes 5.

The circuit 119 now proceeds to identify the position of control valve12, sending a corresponding signal to the authorization circuit 121which in turn transmits to control circuit 122 an order to proceed withthe movement of valve 12 (FIG. 1) into a position in which the measuringvats 2 are placed in connection with a source of negative pressure (notshown). This signal is transmitted to the electromagnetic control deviceof the central valve 12 which is shown schematically in FIG. 1. As soonas control valve 12 has been moved to that position, verifying circuit119 identifies the new position of valve 12, whereupon the circuit 121produces a signal initiating the transfer of the liquid from the testtubes into the measuring vats 2, by starting the device which producesthe negative pressure.

At the end of the predetermined transfer time, the device producing thenegative pressure is cut off and the logic assembly 118 moves thecentral valve 112 to a position in which the individual measuring vatsare separated from each other as well as from the drain tank 15. Thevats were previously communicating with drain tank 15, in order to letany excess liquid contained in the test tubes 5 flow through the vatinto the drain tank, thereby also providing a certain degree ofautomatic rinsing of the vats 2.

Following a time period during which the liquid is allowed to settle inthe measuring vats, the circuit 121 gives a measurement authorizationsignal, the measurement itself being initiated by the generator 120which gives a timed signal at the moment when the platform 17 ispositioned in alignment with the measuring vat 2, assuming that thelatter is vat No. 1 of the series.

The measurement authorization signal initiates the transmission ofelectronic signals from the photosensitive device 58 to the amplifier 59which is mounted on platform 17, and from there, via the rotary contacts27, to the stationary part of the apparatus. The signals are received bythe amplitude-to-time converter 106 which also receives a measurementcontrol signal from circuit 112 for the successive measurement of eachvat. The pulse generator 110 and the AND-gate 108 treat the output ofconverter 106 in such a way that a pulse train is obtained for eachmeasurement which has a timing sequence as given by generator 110, theseparation intervals being determined by the control signals generatedby circuit 112 for vat-by-vat measurement. These pulse trains are thentransmitted to the pulse counter 115 in the logic unit 117, whichreceives a count authorization signal form circuit 116, the latterhaving been initiated by the position verifying circuit 119 of logicunit 118.

The pulses counted by counter 115 are not transmitted to the three-stagecounter 125, 126, 127 and are stored in this counter until the end ofthe measuring operation. The measurement termination signal is producedby circuit 112, and sent to the data recording authorization circuit 114which initiates the transfer of the data stored in counters 126, 126,127 to the tape punch 129 which has been started by circuit 128.

The end result of this operation is a punched tape on which are recordedthe reference or calibration values associated with each separatemeasuring vat 2. The entire series of measuring operations is performedduring one single revolution of platform 17 so that, when the latter isagain in alignment with measuring vat No. 1, the circuit 120 sends a newsignal to circuit 119 which in turn initiates, as previously, theinterruption of the measuring operation, the lowering of the bracket 8,and the movement of central valve 12 in the position where the measuringvats are open to the drain tank (FIG. 1).

The punched tape obtained from punch 129 is now placed on the referencevalue reading device 103, the switch 102 is placed in contact with leads105b and 108b, and the apparatus is ready to perform a new series ofmeasurements on a set of specific test samples. The operations oftransfer and settling of the liquid samples in the measuring vats 2 areperformed in the same manner as previously and are therefore notdescribed again.

On the other hand, however, the measuring operation is now accompaniedby a simultaneous comparison with the reference values which have beenrecorded on the punched tape and which are read by reading device 103.

For this purpose, a control signal from authorization circuit 121 isissued shortly before the transmission of the first measurement from themechanical assembly of the apparatus, the control signal being sent tocontrol circuit 123 which initiates the start up of reader 103, whichthen runs until it produces a first signal corresponding to thereference value of vat No. 1.

This signal is stored and converted by converter 104 and then applied tothe comparator 107 which also receives the measurement signal from thecorresponding first measuring vat 2. The reading operation of reader 103is controlled for all further measuring and comparison operations bymeans of control circuit 113 under the action of pulse generator 112which issues a control signal for the vat-by-vat measurement. Thecircuit 107 thus receives successive pairs of signals, one arriving fromplatform 17 and corresponding to the specific measurement made on asample contained in a vat, while the other arrives from the punched tapewhich contains the reference measurement corresponding to that samemeasuring vat. The output signals of circuit 107 are now measured andstored on a punched tape in exactly the same manner as were the signalsduring the calibration measurement cycle described earlier.

The control device which has been described in reference to FIG. 1 iscomposed of conventional logic circuitry, and no detailed description istherefore given herein.

It can be seen from the above that the apparatus of this invention makesit possible to simultaneously perform a large number of measurements onliquid test samples, these measurements having previously been performedone by one. Thus, this apparatus affords a large saving in time andwages in comparison to prior art devices. It is furthermore possible touse the measuring results which are recorded on punched tape by feedingthem into a computer.

It should be understood, on the other hand, that the apparatus itself,as shown in FIGS. 1-5, may also be controlled in a different manner. Itis possible, for example, to use a computer in order to control both thesequence of operation in the apparatus, and the storing andinterpretation of the measurements obtained. In this case, the analogvoltages produced by the apparatus are directly supplied to theanalog-digital converter of the computer which then makes it possible,among other advantages, to perform several successive measurements oneach measuring vat and to compute an average measurement value for eachof them.

Furthermore, in this case the storage of the reference voltages in thememory is automatic and the division between the reference values andthe corresponding measurement values is obtained by a purely digitaldiscrimination process. Also, the measuring cycle may start at any oneof the measuring vats, the computer taking care of the automaticreclassification of the vats.

Finally, if a suitable computer program is used in connection with acomputer of adequate memory capacity, the computer may be capable ofalso performing all the statistical operations which may be desired inconnection with the interpretation of the measurements made by theapparatus.

In embodiment of the apparatus as described above the platform carries72 measuring vats and the timing of the controls in such that these vatsare measured in 10 seconds. A complete operative cycle thus lastsapproximately 50 seconds, which includes the time necessary for thesettling of the liquid samples inside the vats.

In the case where the use of a computer is considered for the control ofthe apparatus, it is for example possible to perform up to 16measurements on each vat instead of a single one, the entire duration ofan operative cycle being still maintained between 40 and 55 seconds.

It should be understood, of course, that the number of 72 measuring vatsfor the successive measurement of 72 liquid samples is only given by wayof example, and that it would be easy to provide a similar apparatuswith a much larger number of measuring vats based on the teachings ofthis disclosure.

What is claimed is:
 1. An apparatus for measuring a series of liquidtest samples for their light transmission characteristics comprising:a.a stationary circular apparatus frame, b. a plurality of measuring vatsdisposed on said apparatus frame, c. a light source, d. light detectingmeans, e. means for supporting said light detecting means and said lightsource in alignment, .[.and.]. .Iadd.said supporting means comprising:i.a rotary platform journaled in the vertical central axis of saidstationary apparatus frame, ii. said rotary platform having means foraligning said light source and said light detecting means, saidmeasuring vats positioned between said light source and said lightdetecting means for measuring the light transmission characteristics ofsaid vats during rotation of said platform, and iii. said aligning meansdirectly connecting said light source and said light detecting means tosaid rotary platform in fixed, spaced-apart relationship with respect toone another, and .Iaddend. f. .[.means for moving said supporting meansrelative to said measuring vats, said measuring vats positioned betweensaid light source and said light detecting means for measuring the lighttransmission characteristics of said vats.]. .Iadd.means for rotatingsaid platform relative to said apparatus frame during measurement ofsaid light transmission characteristics. .Iaddend.
 2. An apparatus asrecited in claim 1 further comprising:a. means for simultaneouslyfilling all of said measuring vats to be tested with said liquid testsamples.
 3. An apparatus as recited in claim 2 wherein said means forsimultaneously filling said measuring vats comprises:a. a plurality ofconduits, each conduit attached at one end to said vats, b. a pluralityof transfer probes, one transfer probe attached at the other end of eachconduit, c. a bank of sample receptacles for holding said test samplesfor transfer to said vats, d. means for positioning said plurality oftransfer probes within said plurality of sample receptacles, and e.means for forcing said liquid test sample from said sample receptaclesthrough said conduits and into said vats.
 4. An apparatus as recited inclaim 3 wherein said forcing means comprises:a. a source of negativepressure, b. a control valve connected to the source of negativepressure, and c. a suction line connected between each vat and thecontrol valve.
 5. An apparatus as recited in claim 4 further comprisingmeans for simultaneously draining all of said measuring vats.
 6. Anapparatus as recited in claim 5 wherein said draining means comprises:a.a drain line connected between each vat and the control valve, b. adrain connected to the control valve, and c. means for operating thecontrol valve so as to shift it between the following positions:a restposition in which the drain lines are open to the drain, a firstoperating position in which the drain lines are blocked and the suctionlines are simultaneously connected to the source of negative pressure,and a second operating position in which all of the suction lines andall the drain lines are individually blocked.
 7. An apparatus as recitedin claim 6 wherein said control valve is a multi-position rotary valve.8. An apparatus as recited in claim 1 further comprising means forsimultaneously draining all of said measuring vats.
 9. An apparatus asrecited in claim 8 wherein said draining means comprises:a. a controlvalve, and b. a gravity drain line connecting the lower end of each vatto said control valve.
 10. An apparatus as recited in claim 1 whereinsaid .[.supporting.]. .Iadd.aligning .Iaddend.means comprises:.[.a. arotary platform journalled in the vertical central axis of saidstationary apparatus frame,.]. .[.b..]. a bridge on the periphery of therotary platform in the form of an inverted "U" and so arranged on theplatform that the recess of the "U" at least partially encloses the vatprofile, .[.c..]. said light source mounted on one side of the bridge,and .[.d..]. said light detecting means mounted on the other side ofsaid bridge.
 11. An apparatus as recited in claim 10 wherein said lightsource is mounted on said bridge exterior to the periphery of saidrotary platform, and said light detecting means is connected to saidrotary platform and positioned interior to the periphery thereof.
 12. Anapparatus as recited in claim 11 wherein said light detecting meanscomprises:a. a photocell for generating electronic signals in responseto light passing through said vats from said light source. b. means foramplifying said electronic signals, and c. rotary electric contact meansattached to said platform and connected to said amplifying means.
 13. Anapparatus as recited in claim 11 wherein said light detecting meansfurther comprises light condensing means aligned between said photocelland said light source.
 14. An apparatus as recited in claim 11 whereinsaid means for .[.moving.]. .Iadd.rotating .Iaddend.said .[.supportingmeans.]. .Iadd.platform .Iaddend.comprises means for continuouslyrotating said .[.supporting means.]. .Iadd.platform.Iaddend.. 15..[.Apparatus.]. .Iadd.An apparatus .Iaddend.for measuring a series ofliquid test samples for light transmission characteristics comprising:a.a .Iadd.stationary .Iaddend.circular apparatus frame, b. a plurality ofmeasuring vats .[.positioned.]. .Iadd.disposed .Iaddend.on saidapparatus frame, c. a light source, d. light detecting means, e. meansfor supporting said light detecting means and said light source inalignment, .Iadd.said supporting means comprising:i. a rotary platformjournaled in the vertical central axis of said stationary apparatusframe, ii. said rotary platform having means for aligning said lightsource and said light detecting means, said measuring vats positionedbetween said light source and said light detecting means for measuringthe light transmission characteristics of said vats during rotation ofsaid platform, and iii. said aligning means directly connecting saidlight source and said light detecting means to said rotary platform infixed, spaced-apart relationship with respect to one another, and.Iaddend. f. means for .[.effecting relative motion between thesupporting means and the measuring vats, whereby said vats are alignedbetween said light source and said light detecting means duringmeasurement,.]. .Iadd.rotating said platform relative to said apparatusframe during measurement of said light transmission characteristics,.Iaddend. g. means for simultaneously filling all of said measuringvats, and h. means for simultaneously draining all of said measuringvats.
 16. An apparatus as recited in claim 15 wherein said means forsimultaneously filling all of said vats comprises:a. a plurality ofconduits each conduit attached at one end of said vats, b. a pluralityof transfer probes, one transfer probe attached at the other end of eachconduit, c. a bank of sample receptacles for holding said test samplesfor transfer to said vats, d. means for positioning said plurality oftransfer probes within said plurality of sample receptacles, and e.means for forcing said liquid test sample from said sample receptaclesthrough said conduits and into said vats.
 17. An apparatus as recited inclaim 16 wherein said forcing means comprises:a. a source of negativepressure, b. a control valve connected to the source of negativepressure, and c. a suction line connected between each vat and thecontrol valve.
 18. An apparatus as recited in claim 17 wherein saiddraining means comprises:a. a drain line connected between each vat andthe control valve, b. a drain connected to the control valve, and c.means for operating the control valve so as to shift it between thefollowing positions:a rest position in which the drain lines are open tothe drain, a first operating position in which the drain lines areblocked and the suction lines are simultaneously connected to the sourceof negative pressure, and a second operating position in which all ofthe suction lines and all the drain lines are individually blocked. 19.An apparatus as recited in claim 18 wherein said control valve is amulti-position rotary valve.
 20. An apparatus as recited in claim 15wherein said draining means comprises:a. a control valve, and b. agravity drain line connecting the lower end of each vat to said controlvalve. .[.21. An apparatus as recited in claim 15 wherein saidsupporting means is movable and said apparatus frame is stationary..].22. An apparatus as recited in claim .[.21.]. .Iadd.15 .Iaddend.whereinsaid supporting means comprises:.[.a. a rotary platform journalled inthe vertical central axis of said stationary apparatus frame,.]..[.b..]. .Iadd.a. .Iaddend.a bridge on the periphery of the rotaryplatform in the form of an inverted "U" and so arranged on the platformthat the recess of the "U" at least partially encloses the vat profile,.[.c..]. .Iadd.b. .Iaddend.said light source mounted on one side of thebridge, and .[.d..]. .Iadd.c. .Iaddend.said light detecting meansmounted on the other side of said bridge.
 23. An apparatus as recited inclaim 22 wherein said light source is mounted on said bridge exterior tothe periphery of said rotary platform, and said light detecting means isconnected to said rotary platform and positioned interior to theperiphery thereof.
 24. An apparatus for measuring a series of liquidtest samples for their light transmission characteristics comprising:a.a stationary circular apparatus frame, b. a plurality of measuring vatspositioned in a circular locus near the periphery of said apparatusframe, c. an optical system comprising:i. a first element comprising alight source, and ii. a second element comprising light detecting meansand light condensing means, d. means for supporting said first andsecond elements in alignment, .[.one of said elements positionedexterior to the locus of said vats and the other element positionedinterior to the locus of said vats, and.]. .Iadd.said supporting meanscomprising:i. a rotary platform journaled in the vertical central axisof said stationary frame; ii. said rotary platform having means foraligning said light source and said light detecting and light condensingmeans, said measuring vats positioned between said light source and saidlight detecting and light condensing means for measuring the lighttransmission characteristics of said vats during rotation of saidplatform, and iii. said aligning means directly connecting said lightsource and said light detecting and light condensing means to saidrotary platform in fixed, spaced-apart relationship with respect to oneanother, and .Iaddend. e. means for .[.continuously moving saidsupporting means relative to said measuring vats, said measuring vatspositioned between said light source and said light detecting means formeasuring.]. .Iadd.continuously rotating said platform relative to saidapparatus frame during measurement of .Iaddend.said light transmissioncharacteristics.
 25. An apparatus as recited in claim 24 furthercomprising:a. means for simultaneously filling all of said measuringvats to be tested with said liquid test samples.
 26. An apparatus asrecited in claim 25 wherein said means for simultaneously filling saidmeasuring vats comprises:a. a plurality of conduits, each conduitattached at one end to said vats, b. a plurality of transfer probes, onetransfer probe attached at the other end of each conduit, c. a bank ofsample receptacles for holding said test samples for transfer to saidvats, d. means for positioning said plurality of transfer probes withinsaid plurality of sample receptacles, and e. means for forcing saidliquid test sample from said sample receptacles through said conduitsand into said vats.
 27. An apparatus as recited in claim 26 wherein saidforcing means comprises:a. a source of negative pressure, b. a controlvalve connected to the source of negative pressure, and c. a suctionline connected between each vat and the control valve.
 28. An apparatusas recited in claim 27 further comprising means for simultaneouslydraining all of said measuring vats.
 29. An apparatus as recited inclaim 28 wherein said draining means comprises:a. a drain line connectedbetween each vat and the control valve, b. a drain connected to thecontrol valve, and c. means for operating the control valve c. means foroperating the control valve so as to shift it between the followingpositions:a rest position in which the drain lines are open to thedrain, a first operating position in which the drain lines are blockedand the suction lines are simultaneously connected to the source ofnegative pressure, and a second operating position in which all of thesuction lines and all the drain lines are individually blocked.
 30. Anapparatus as recited in claim 24 wherein said supporting meanscomprises:.[.a. a rotary platform journalled in the vertical centralaxis of said stationary apparatus frame,.]. .[.b..]. .Iadd.a. .Iaddend.abridge on the periphery of the rotary platform in the form of aninverted "U" and so arranged on the platform that the recess of the "U"at least partially encloses the vat profile, .[.c..]. .Iadd.b..Iaddend.said light source mounted on one side of the bridge, and.[.d..]. .Iadd.c. .Iaddend.said light detecting means mounted on theother said of said bridge.
 31. An apparatus as recited in claim 30wherein said light source is mounted on said bridge exterior to theperiphery of said rotary platform, and said light detecting means isconnected to said rotary platform and positioned interior to theperiphery thereof. .Iadd.
 32. An apparatus as recited in claim 24wherein said light condensing means comprises an optical fiber fordirecting light from the measuring vats to said light detecting means..Iaddend..Iadd.
 33. An apparatus as recited in claim 24 wherein saidfirst element further comprises optical means for directing a light beamfrom said light source to said measuring vats. .Iaddend..Iadd.
 34. Anapparatus as recited in claim 29 wherein said means for positioning saidtransfer probes within said plurality of sample receptacles comprisesmeans for supporting said sample receptacles below said transfer probesand motor means for moving said sample receptacle supporting meansupwardly for positioning said transfer probes within said samplereceptacles. .Iaddend..Iadd.
 35. An apparatus as recited in claim 34wherein there is one transfer probe and one sample receptaclecorresponding to each measuring vat, all of said sample receptaclesbeing supported on said sample receptacle supporting means forsimultaneous vertical movement by said motor means. .Iaddend. .Iadd. 36.An apparatus for measuring a series of liquid test samples for theirlight transmission characteristics comprising:a. a stationary circularapparatus frame, b. a plurality of measuring vats disposed on saidapparatus frame, c. means for filling all of said measuring vats to betested with said liquid test samples, d. means for draining all of saidmeasuring vats, e. a light source, f. a light detecting means, g. meansfor supporting said light detecting means and said light source inalignment, said supporting means comprising:i. a rotary platformjournaled in the vertical central axis of said stationary apparatusframe, ii. said rotary platfrom having means for aligning said lightsource and said light detecting means, said measuring vats positionedbetween said light source and said light detecting means for measuringthe light transmission characteristics of said vats during rotation ofsaid platform, andiii. said aligning means directly connecting saidlight source and said light detecting means to said rotary platform infixed, spaced-apart relationship with respect to one another, and h.means for moving said supporting means relative to said measuring vatswhereby light emitted by said light source is received by said lightdetecting means after passing through said measuring vats for measuringthe light transmission characteristics of said vats. .Iaddend.